Attempts have been made recently, for safety reasons, to provide closures for containers which make it difficult for small children to remove the closures to gain access to the containers and to their possibly harmful contents. All of these suffer, however, in some degree from the problem that it may be too easy for the child to remove the closure and too difficult for many adults to do so. Also, they tend to be difficult to make and therefore become expensive because of their complicated form. Furthermore, many often require modification of the container itself which is not desirable.
The present invention solves these problems by presenting a closure which does not require modification of the container to which it is to be attached, is not difficult for an adult to use, is simple in construction and should be relatively inexpensive to manufacture.
A U.S. patent on an invention which attempts to solve these problems was issued to Maurice Steiner under Ser. No. 3,399,769 on Sept. 3, 1968 and shows, as part of its disclosure, two parts of the sidewall of the closure which can be distorted upwardly to bring into alignment portions of the thread on the inside of the closure so that the closure can be unscrewed from a container. This arrangement differs from the device shown in the present invention in a number of important respects such as, for instance, the fact that the partial thread of the present invention is not deformed nor distorted in any way. Furthermore, alignment of the partial thread is completely automatic in the present invention whereas in the Steiner showing the operator, or installer of the closure, must bend the thread portion upward and aim the thread into position.
Other differences exist as well and will become apparent from the description and claims concerning the present invention which follow in this application.